<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    #app{
      width:100px;
      height:200px;
      background-image: radial-gradient(closest-side at 60% 55%, blue, green, yellow, black);
    }
    #app2{
      width:100px;
      height:200px;
      background-image: radial-gradient(circle, red, yellow, green);
    }
  </style>
</head>
<body>
  background-image: radial-gradient(closest-side at 60% 55%, blue, green, yellow, black);
  <div id="app">

  </div>
  background-image: radial-gradient(circle, red, yellow, green);
  <div id="app2">

  </div>
</body>
</html>